Kun-Ho Liu

Instantaneous Drug Delivery of Magnetic/Thermally Sensitive Nanospheres by a High-Frequency Magnetic Field

Novel dual-functional nanospheres composed of magnetic iron oxide nanoparticles embedded in a thermo-sensitive Pluronic F127 (F127) matrix were successfully synthesized by an in situ coprecipitation process. The nanospheres were characterized by X-ray diffraction, transmission electron microscopy, X-ray photoelectron spectroscopy, and Raman spectroscopy. Experimental observations indicated that the F127 was subjected to a rapid structural change when the magnetic phase caused rapid heating after a short exposure to a high-frequency magnetic field. During the field duration, considerable volume shrinkage of the nanospheres (2.3-fold diameter reduction) was detected. This has been translated to an instantaneous release of a drug, Doxorubicin (DOX), when the DOX was encapsulated within the nanospheres. Such a rapidly responsive release of the DOX from the nanospheres was due to an intimate contact between the nanomagnet and F127, where an effective thermal and mechanical transfer between core and shell phases efficiently took place in the presence of the magnetic field.

Chitosonic® Acid as a Novel Cosmetic Ingredient: Evaluation of its Antimicrobial, Antioxidant and Hydration Activities

Chitosonic® Acid, carboxymethyl hexanoyl chitosan, is a novel chitosan material that has recently been accepted by the Personal Care Products Council as a new cosmetic ingredient with the INCI (International Nomenclature of Cosmetic Ingredients) name Carboxymethyl Caprooyl Chitosan. In this study, we analyze several important cosmetic characteristics of Chitosonic® Acid. Our results demonstrate that Chitosonic® Acid is a water-soluble chitosan derivative with a high HLB value. Chitosonic® Acid can form a nano-network structure when its concentration is higher than 0.5% and can self-assemble into a nanosphere structure when its concentration is lower than 0.2%. Chitosonic® Acid has potent antimicrobial activities against gram-positive bacteria, gram-negative bacteria and fungus. Chitosonic® Acid also has moderate DPPH radical scavenging activity. Additionally, Chitosonic® Acid exhibits good hydration activity for absorbing and retaining water molecules with its hydrophilic groups. From a safety point of view, Chitosonic® Acid has no cytotoxicity to L-929 cells if its concentration is less than 0.5%. Moreover, Chitosonic® Acid has good compatibilities with various normal cosmetic ingredients. Therefore, we propose that Chitosonic® Acid has the potential to be a widely used ingredient in various types of cosmetic products.

Synthesis and characterization of mesoporous Gd2O3 nanotube and its use as a drug-carrying vehicle.

Gd2O3 nanotubes were constructed for the first time by assembling highly crystalline Gd2O3 nanoparticles through the use of combined soft template and sol-gel methods. Amphiphilic block copolymer was used as structure-directing agent and gadolinium isopropoxide as inorganic precursor in non-aqueous solution. The amphiphilic copolymer molecules are known to undergo self-organization above a critical micelle concentration, forming micellular architecture that further provides a structurally ordered active site for the nucleation and growth of Gd monomers. The resulting self-assembly of the Gd2O3 nanocrystals led to the formation of Gd2O3 tubular nanostructure after pyrolytic removal of the template. Transmission electron microscopy analysis indicated a mesoporous channel array along the [110] direction of the nanotubes where the wall of nanotube is well organized by the assembly of a highly crystalline framework of Gd2O3 nanocrystals. This Gd2O3 nanotube exhibited weak superparamagnetic property and was found to be able to carry and elute a model molecule, i.e. ibuprofen (IBU), in a controllable manner via an external magnetic field. The mechanism of IBU release from the nanotubes with and without the use of magnetic stimulus was proposed.

Improved Thermostability of deoxyArbutin by Self-assembled Carboxymethyl Caprooyl Chitosan and Oil Formulation

Tyrosinase is a key enzyme that is mainly involved in the formation of melanin. Many compounds have established inhibitory effects on melanogenesis through inhibitory activity for tyrosinase. DeoxyArbutin (dA) reveals greater inhibition of tyrosinase activity and to be safer than arbutin and hydroquinone. However, deoxyArbutin was thermolabile in aqueous solutions and decomposes to hydroquinone. Therefore, to increase the stability of deoxyArbutin in formulations, we chose two systems, self-assembled Chitosonic® Acid (Carboxymethyl Caprooyl Chitosan) capsules and oil formulation, as the formulations for investigation. The self-assembled Chitosonic® Acid nanospheres can successfully decrease the decay of deoxyArbutin in aqueous solution. Besides, for oil formulation, whole oil solution can obviously protect deoxyArbutin from the heat stimulated decomposition in its environment and then reduce the level of released hydroquinone in deoxyArbutin containing formulation. Therefore, our results demonstrated that both two potential systems can improve the thermostability of deoxyArbutin.

Formation of Zn-ZnO Polygon Prismatic Nanocrystals by Liquid Source via Thermal Vapor Transport

A novel hierarchical polygon prismatic nanostructure of wurtzite Zn has been grown on silicon by liquid-solution seed nucleation and vapor-gas growth method. The Zn(ClO4)2 colloidal sol with various concentrations was used as seeds to control the dimension of Zn crystals from the nanometer (30 nm) to micrometer scale (2 µm). Depending on heat-treatment temperature, different morphology was developed. In the temperature range of 200-300oC, a compact polygon prismatic Zn structure was formed. However, in a high temperature range of 300-400oC, polygon prismatic Zn with hollow structure was observed. After oxidation treatment, the ZnO surface layer can be developed on the Zn nanocrystals to form ZnO-Zn core-shell structure as evidenced from PL measurement. These formed ZnO-Zn nano- and micro-crystals can be further used as building blocks to assemble two- or three-dimensional photonic crystals. PACS codes: 81.10.Aj, 64.70.Fx, 64.72.-y